Github user cestella commented on the issue:
https://github.com/apache/metron/pull/740
So, one way to do this is to allow users to refer to stellar fields:
```
my_complex_field := { 'blah' : 7 }
%define nicks_new_global_field=&my_complex_field
```
Another option to support this is to just insist that `%define` is a string and you have
a `replace_global` that takes a field as an argument and the field contains the new global
config (in JSON form) and replaces the global config:
```
new_global_config := SHELL_EDIT()
%replace_global new_global_config
```
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